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How Quickly Do You Lose Muscle Tissue?


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(First of, hope this is in the right forum. Feel free to move it if it is not.)

I'm sick, so right now I'm maintaining so as not to gain weight while I get better. And while the scale isn't going up, it's been a while now since I've been able to truly work out, and I'm starting to worry that I'm changing muscles for fat without realising it.

I eat well and enough - never go to bed hungry (or I can't sleep) and I never feel faint. Right now I'm at about 1500 cal/day since I'm sedentary, so I'm not starving myself in the fear of gaining weight during my 'time off'. Honestly, I'd rather gain regular weight but keep the muscles as they are, because that would be easier to work off than to rework out the muscles.

Since I'm really not using my muscles right now as I've gotten used to (through walking mostly), will it lead to muscle loss, even if I'm not keeping my body from the nutrients and such I really need?

And what happens if I one day that I'm still eating my 1500cal of maintenance end up walking more than I "should" (that one single day) - will it too affect my muscles in a negative way? Is it something that can change the next day (not reverse, but not continue) or will it only get worse?

I'm assuming it's a faster process of losing the tissue than it is to gain it, but by how much? In a general sort of way, since it's probably different for everyone depending on how much muscle they have from the start.

So basically, how immediately does the body start breaking down muscle tissue for fuel?

Is it something I should be worried about?

3 Replies (last)

"I'm assuming it's a faster process of losing the tissue than it is to gain it, but by how much?"

Well, if you think about it, if that were  true all our ancestors would have been wiped out, coz they'd build up muscles when the hunting was good, and they were very active and eating well, but then they'd have wasted away during a tougher time (like winter, when they were limited on activity and food) before the prey came back!

I'm not saying that to be facetious, I just think we often get caught up in modern views on how precious we are and forget that our bodies are primarily survival machines. The thread I posted about metabolism versus pure cals in/out demonstrates that - our bodies know what they're doing in times of reduced intake or exercise, they don't give up that easily.

I know I still have more developed muscles in my arm from doing phsyio intensively after I broke it 10+ years ago, despite not having maintained anything like the same level of workout after that finished.

Our bodies have fat stores for a reason - to feed us when times are tough. Only slender people who diet too harshly are apt to break down muscle equally with fat, most people's metabolism will go for the fat first - look at it this way, your body metabolises fats quicker and easier than protein, and even though breaking down your own cells doesn't involve the GI tract, it's still not going to start munching away on your biceps etc if there's any fat handy, and so long as you're eating a healthy amount.

And most of us know it's easier to gain 10lbs of fat than 10lbs of muscle, fat is fairly simple stuff, your body just fills pre-existing fat cells, whereas building muscle is complex and demanding, and our bodies won't undo all that hard work as readily under normal circs. That's a bit oversimplified, but generally true.

You know, it's kinda funny, 'cause just earlier today I was thinking about cavemen people (or the like) and how they must've been able to survive without working out in our sense.

Thanks for the reply, at least I know not to worry about it. :)

I've not seen that thread of yours, but I'll be sure to check it out.

I don't know if this is true, but I think your body will probably only burn fat if you are sedentary (heart rate not that fast).  I think one's body will start to burn muscle for fuel after it has been in a steady state of high heart rate.  At that point in time I believe it is easier for the body to break muscle tissue down into glycogen than fat.  But if you aren't doing much I think you're safe.

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